Effects of X-irradiation on rat hair follicles.

The alterations of normal growth of hair follicles following irradiation of rat tails with X-rays have been analysed. The changes in follicle length are attributed to a series of deleterious events occurring in the hair matrix after irradiation. A dose-dependent reduction of length was demonstrated for a given post-irradiation interval. An approximate exponential response was obtained for all conditions excepting low doses for which a marked reduction of follicle length was observed a short time after irradiation and was ascribed to the depletion of highly radiosensitive cells. At later post-irradiation times this response was obscured by the resumption of follicle growth.